This invention relates to machine lubrication systems of engines, compressors and the like machinery, including an oil-like-lubricant pressure line communicated with a reservoir by means of a means for maintaining the working properties of the lubricant.
The latter means in known such systems (C. F. Taylor, The Internal Combustion Engine in Theory and Practice, The MIT Press, Cambridge, Massachusetts, 1966; K. Abrosimov, A. Bromberg, F. Katayev, Road-Making Machinery, Mir Publishers, 1971; M. Khovakh, Motor-Vehicle Engines, Mir Publishers, 1971; B. Gelman and M. Moskvin, Farm Tractors, Mir Publishers, Moscow, 1975; U.S. Pat. Nos. 3,400,285, 3,356,182, etc.) removes solid contaminants from lubricant by filtering, straining, gravitational displacement, centrifugal separation, etc. with full-flow and bypass (5-20% of the flow).
This removing is very important because the reliability and longevity of both lubrication systems and the machines they take care of depend on the working properties of the lubricant in many respects. These properties are determined by the presence of solid, gaseous and liquid contaminants in lubricant, the state of their dispersion and fineness.
The solid contaminants are the products of wear and oxidation of both the details and lubricant, or are the dust from the atmosphere. The solid contaminants are abrasive, cause wear, decrease the term of unit service, can wedge movable details (especially plunger ones) and cause inoperativeness of automatic controls.
Above known means being unable to remove all the contaminants from lubricant are assumed to be qualified if the size of the removed solids is more than the clearance in the sliding pairs of the machinery, although the gaseous and liquid contaminants are left in lubricant. Fine-mesh bypass filters used in many cases are much-energy-consuming, require their frequent changes because of their clogging and becoming a repository for biological growth in some areas.
Gaseous contaminants (air, carbon dioxide, sulphur dioxide, water vapor, etc.) are absorbed from the atmosphere or from their internal source (e.g. incomplete combustion process). If unsolved, they deteriorate the pliability, triggering and stability of lubrication systems and can cause their inoperativeness.
Some gaseous contaminants (e.g. sulfur dioxide) form acids (causing corrosion) with water. Besides, oxygen solubility in liquid is higher than that of atmosphere air, dissolved air containing 40-50% more oxygen. This intensifies oxidation of oil and details.
Also, the gas form foam decreasing lubrication ability and causing corrosion of details and oxidation and other chemical reactions in oil because of bigger interface and more oxygen content. In time the stable foam forms viscous contaminants depositing on detail surfaces. The foamforming is sharply increased by the presence of water (even at only 0.1%).
Gas is always present in liquid, at least dissolved, and usually does not affect the mechanical properties of liquid. However, vibration, decreasing pressure and heating give the gas off (even with foaming) and form the inoperative mixture instead of former solution fitted for work. That is why the problem especially arises in lubrication systems of vehicles when the systems remaining inoperative are subjected to jarring and vibration if there is an auxiliary engine.
The main representatives of liquid contaminants are water coming into tank in its vapor form and condensing when the temperature drops, and fuel which can come into lubrication systems from combustion chambers or because of leakage.
The effect of water is above foaming. Fuel volatile, its effect is that of gaseous contaminants.
In spite of described deterioration by gaseous and liquid contaminants, most lubrication systems have only solids-filtering devices ignoring other contaminants.